This invention relates generally to apparatus and methods for completing downhole wells, and more particularly relates to flow conductors for conveying inflowing formation fluid in water, oil, gas and recovery wells.
In the course of completing an oil and/or gas well, it is common practice to run a string of protective casing or liner into the well bore and then to run production tubing inside the casing. The annulus between the liner or casing and the surrounding formation is sealed with a deposit of cement to prevent fluid flow through the external annulus from one formation zone to another. The cement is pumped through a work string suspended within the casing or liner into the annular space between the liner or casing and the surrounding well bore.
If the lining or casing traverses a hydrocarbon-bearing formation, the lining is perforated to create flow apertures through the casing and cement so that the formation fluids can flow into the well. The liner and/or well casing is perforated by a perforating gun which is suspended within the well. Shaped explosive charges carried by the gun blast openings through the metal lining, the cement deposit and the surrounding formation.
In some completions, however, the well bore is uncased, and an open face is established across the oil or gas bearing zone. Uncased arrangements of this type may be utilized, for example, in water wells, test wells and horizontal/deviated well completions. In one form of such uncased completions, a relatively small diameter flow conductor is suspended within the uncased bore hole and cement is pumped through the flow conductor into the annulus between the flow conductor and the surrounding earth formation. After cement residue is cleaned from the flow conductor, the flow conductor and the surrounding cement deposit are perforated to admit formation fluid into the well.
Because of the economies associated with this type of uncased completion, there is a continuing interest in improving the flow conductors used in such completions. There is a need in such completions for a small diameter nipple, incorporated in the well flow conductor, which can be used in vertical as well as deviated uncased well bores, and reliably perforated by a small diameter perforating gun. There is also a need for apparatus and methods for closing off the flow openings in a small diameter nipple of the type described. It is accordingly an object of the present invention to provide such a nipple and associated flow opening closure apparatus and methods.